1. Field of the Invention
The present invention relates to an optical imaging lens system, and more particularly, to a compact optical imaging lens system used in an electronic product.
2. Description of the Prior Art
The demand for compact imaging lenses has grown in recent years as the popularity of portable electronic products with the photographing function has increased, and the sensor of a general photographing camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor Sensor). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced, and the resolution of compact imaging lens element has gradually increased, there is an increasing demand for compact imaging lens system featuring better image quality.
A conventional compact imaging lens for portable electronic products generally comprises three lens elements. The lens system, as the one disclosed in U.S. Pat. No. 7,145,736, in order from an object side to an image side includes a first lens element with positive refractive power, a second lens elements with negative refractive power and a third lens elements with positive refractive power. With the advance of semiconductor manufacturing technology and the trend of design toward compact in electronic products, the pixel size of sensors become smaller and the standard of requirement for image quality become higher. Therefore, the conventional systems of three lens elements no longer satisfy the higher level camera modules.
U.S. Pat. No. 7,365,920 discloses a four lens elements system, wherein two spherical-surface glass lenses serving as the first and second lens elements are adhered together to form a doublet for correcting the chromatic aberration. Such an arrangement of optical elements, however, has the following disadvantages: (1) the degrees of freedom of the system is curtailed due to the excessive employment of spherical-surface glass lenses, thus the total track length of the system is hard to be reduced; (2) the process of adhering glass lenses together is complicated, posing difficulties in manufacture.
Therefore, a need exists in the art for an optical image lens system that features better image quality, maintains a moderate total track length and is applicable to compact portable electronic products.